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use crate::*; use std::marker::PhantomData; pub struct Expect<T, F>(F, PhantomData<T>) where T: Clone, F: Fn(&T) -> bool; impl<T, F> Expect<T, F> where T: Clone, F: Fn(&T) -> bool, { pub(crate) fn new(f: F) -> Self { Self(f, PhantomData) } } impl<T, F> Scanner for Expect<T, F> where T: Clone, F: Fn(&T) -> bool, { type Input = T; type Output = T; fn scan(&self, stream: &mut Stream<Self::Input>) -> Res<Self> { let val = stream .peek() .ok_or_else(|| Error::new(stream.pos(), None, Expected::Unknown))?; if self.0(&val) { stream.next(); Ok(val) } else { Err(Error::new(stream.pos(), Some(val), Expected::Unknown)) } } }